Integumentary Lab PDF

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Integumentary system-lab pics and review...

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Lab 3: Integumentary System Information Integument Model I. The skin is composed of an epidermis and a dermis. The epidermis is the outermost layer of the skin and consists of keratinized stratified squamous epithelial tissue. Thus, there are no blood vessels in the epidermal layers. The dermis of the skin is more complex than the epidermis because it contains many skin appendages such as hair follicles, glands, blood vessels, and nerves. The dermis consists of two layers: an outer papillary layer and an inner reticular layer composed of areolar and dense irregular connective tissues, respectively. Deep to the dermis is the hypodermis, a layer of areolar and adipose tissue that is not considered part of the skin.

Figure: Integument Model. The left side of this model demonstrates thick skin, which has five epidermal layers. The right side of this model demonstrate thin skin, which has only four epidermal layers and contains hair follicles.

The Epidermis II. The main cell type composing the keratinized stratified squamous epithelial tissue of the epidermis is keratinocyte, named for its role is synthesizing the protein keratin. Keratin is an insoluble protein that imparts strength to the skin and makes it water resistant. Other cell types in the epidermis include melanocytes that produce the pigment melanin, and tactile (Merkel) cells that release chemicals to simulate nerve endings when compressed. The epidermis of thick skin is located only on the palms of the hands and soles of the feet and has five distinct layers. In contrast, the epidermis of the skin is located on all other areas of the body’s surface and has four layers. Layers of the Epidermis

Figure: Epidermal layers in thick skin (found on the palms of the hands and soles of the feet).

Pigmented Skin III. The color of a person’s skin is a partially due to the pigment melanin. Melanin is produced by cells called melanocytes, which are found within the stratum basale of the epidermis. Differences in skin color have to do with the amount of melanin produced by melanocytes and how quickly the melanin is broken down. The melanocytes of dark-skinned individuals simply produce greater amounts of melanin that is broken down more slowly than those of light-skinned individuals.

Figure: Pigmented skin. Pigmented skin containing melanin granules (brown) within keratinocytes, particularly in the basale of the epidermis. Melanocytes themselves are distinguished by a halo of a clear cytoplasm that surrounds the nucleus. The Dermis IV. The dermis consists of two layers: an outer papillary layer, and an inner reticular layer. The papillary layer is the part of the dermis that contain “nipplelike” extensions that project upward into the epidermis (the dermal papillae). The papillary layer is generally quite thin and is composed of areolar connective tissue. The reticular layer is named for its “networked” appearance not because it contains reticular fibers. In fact, the major fiber type found in this layer is the collagen that composes dense irregular connective tissue. These collagen fibers are interwoven into a meshwork that surrounds structures of the dermis such as hair follicles, sweat glands, sebaceous glands, blood vessels, and nerves. The slide descriptions in this section of the laboratory serve as a guide both for general observation of the structure and function of the dermis and for identification of the various skin appendages found within the dermis.

Figure: Dermis. Thick skin demonstrating several skin appendages, such as lamellated corpuscles and merocrine sweat glands in the dermis.

Layers of the Dermis

Figure: Tactile Corpuscle. High magnification view of a dermal papilla containing a tactile corpuscle.

Table: Lists the types of glands located in the dermis and describes their locations and functions.

Table: Summarizes the characteristics of sensory receptors in the dermis.

The Scalp- Hair Follicles and Sebaceous Glands

Figure: Scalp. Skin of the scalp, demonstrating several hair follicles. Arrector pili muscles are not visible in this photomicrograph.

Figure: Close-up View of a Hair Bulb.

Figure: Apocrine Sweat Gland. Axillary skin demonstrating apocrine sweat glands....